Front derailleur again!

[Baldy]

On my mountain bike, goes up from small to middle to large ring no trouble.

Coming down, from large ring, one click, nothing happens. Another click and it drops straight to the small ring.

My other bikes only have two rings at the front and I've never had any trouble with them. With the mountain bike this problem develops after about 50 miles. I mess about with it for ages before having to take it to the shop. I can't keep doing this, what am I doing wrong?

 

[Gunk]

Sounds like the cable is sticking. Undo the cable and see if the mech moves freely when it’s disconnected.

if it does, remove the inner cable and clean it with some wire wool, wipe it with oil and reassemble it.

 

[Baldy]

Ok, l'll try that.

 

[Gunk]

If you disconnect the cable and the mech is not moving freely, remove it from the bike, thoroughly clean and degrease it, lightly oil it and it should be fine.

 

[si_c]

Sounds like your cable housing could need replacing, when you click to go down a gear the spring in the derailleur pulls the cable out and the arm moves inwards, if there is too much friction in the system then the arm won't swing in as the spring isn't strong enough. Usually this means new cables, but you can try lubricating the cables - gt80 or wd40 should do it.

 

[Baldy]

Well, checked cable, checked mech both seem fine. I've been trying to follow this
View: https://youtu.be/ZNG7g83lI-s
still getting no where.

 

[Baldy]

Well I think I've got it working, no idea how or why it keeps going out of line. Local bike shops are all closed so I can't take it in and get it checked. So, I've no idea where to go from here.

 

[Gunk]

If it’s working then you’ve fixed it!